1. Field of the Invention
The present invention relates to a member for use in a semiconductor producing system that is provided around a susceptor for mounting a semiconductor, in a semiconductor producing chamber.
2. Related Art Statement
In a semiconductor producing system, it is known to mount a semiconductor wafer on a ceramic heater to heat the wafer when a semiconductor thin film is produced on the wafer from gaseous raw materials such as silane gas by means of thermal CVD or the like (i.e., a direct heating system). So-called multi-zone heaters have been known as ceramic heaters used in such direct heating systems. Such a multi-zone heater includes a ceramic substrate having inner and outer resistance heat generators made of high melting point metals embedded within the substrate. Separate power supply terminals are connected to the respective heat generators so that electric power may be applied independently on the respective heat generators. The inner and outer heat generators may be thus independently controlled.
In JP-A 5-326112, a resistance heat generator of a ceramic heater is constituted by a plurality of circuit patterns, each made of a high melting point metal. The circuit patterns are arranged so that they may supplement one another's defect portions. For example, one of the patterns has a defect portion such as a folded portion or a returning portion. In this case, another circuit pattern is overlapped on or over the defect portion of the one pattern.
For example, in a heater to be used for heating semiconductor wafers, the temperature of the heating face of the heater needs to be uniformly controlled over the entire surface. It is required that the heater satisfy a severe specification, for example, that the temperature measured on the heating face is within ±5° C. of the average of the whole heating face under a use condition.